Ultrahigh-capacity semi-solid SiOx anolytes enabled by robust nanotube conductive networks for Li-ion flow batteries

Exploring semi-solid anolytes with high volumetric capacity and low potential is of great significance for boosting the energy storage capability of Li-ion flow batteries. Generally, micro-sized SiOx shows promises in fabricating high-capacity anolytes owing to its inherent advantages in specific capacity, processability and cost. However, its poor electronic conductivity and huge volume change result in unexpected issues of loss of electrical connections, structural disintegration, and unstable solid-electrolyte interphase (SEI). Herein, these issues are addressed by constructing robust conductive networks throughout anolytes by employing single-walled carbon nanotubes (SWCNT) as conductive additives. Compared with loose networks constructed by KB, such robust networks can facilitate continuous electrons transport and improve particle integrity. SiOx anolytes with robust networks display an ultrahigh capacity, excellent rate capability, and stable cyclability in static cells. Furthermore, as-prepared anolytes can simultaneously achieve suitable viscosity and superior electronic conductivity. The assembled flow cell demonstrates high volumetric capacities of 74.7–98.0 Ah L−1 under the static test and the feasibility in long-term continuous-flow mode. Our successful demonstration of SiOx semi-solid anolytes may be helpful for the construction of high-energy-density flow batteries.